The research proposed in this grant combines the study of the nutrient related physiology of the gastrointestinal tract with the demonstration of the influence of relevant aspects of this physiology coordinated in feeding behavior. The view that informs this work is that feeding functions to maintain caloric homeostasis in the organism via the mediation of central nervous system mechanisms but must accomplish this goal through the integrated activity of several bodily compartments. The experiments devised here will (1) explore in the rhesus monkey the capabilities of the gastrointestinal tract for the management of intraluminal calories in a quantitative and coordinated way, (2) relate these capabilities to the satiety for food in meal taking, (3) describe any role of such GI hormones as secretin and bombesin in relating the management of calories by the gastrointestinal tract to feeding, (4) study the effect of interrupting the gastric vagus on this coordination in gastrointestinal function, and (5) study patients with nutritional disorders (particularly anorexia and alimentary hypoglycemia) for abnormalities in these functions. These studies are attempts to discern aspects of basic physiology that may be crucial in the regulation of food intake and abnormal in human nutritional and metabolic conditions such as obesity, diabetes mellitus, and anorexia.